1. Field of the Invention
The present invention relates to an optical deflector which changes a direction of a mirror surface irradiated with a light beam to change the direction of a reflected light beam.
2. Description of the Related Art
A concept of manufacturing an optical deflector by silicon micro-machining was presented by K. Petersen around 1980. In recent years, a practical optical deflector has been developed, and a remarkable progress has also been made in a manufacturing process. However, presently, it cannot be said that there is an established method regarding a mounting technique.
The present applicant has disclosed an electromagnetic driving type optical deflector in U.S. Pat. No. 6,122,089. This deflector will be described hereinafter with reference to FIGS. 13 to 15.
The optical deflector includes an optical deflector mirror portion 100 formed of a single-crystal silicon substrate, and the optical deflector mirror portion 100 includes a movable plate 101, a pair of elastic members 102 and a pair of supports 103. The movable plate 101 has a driving coil 104 on a lower surface thereof (lower surface in FIGS. 14 and 15), and a mirror surface 106 on an upper surface thereof (upper surface in FIGS. 14 and 15).
As shown in FIG. 15, the support 103 of the optical deflector mirror portion 100 is bonded/fixed to a U-shaped fixing member 111. In order to prevent the fixing member 111 from blocking a light beam incident upon the mirror surface 106 and a light beam reflected by the mirror surface 106, the optical deflector mirror portion 100 is attached to the fixing member 111 in such a manner that the surface of the movable plate with the driving coil 104 formed thereon necessarily turns to the fixing member.
The optical deflector further includes a magnetic circuit including a permanent magnet 108 and magnetic yokes 109, 110. As shown in FIG. 14, the magnetic yoke 110 extends in the vicinity of the movable plate 101 through the fixing member 111 in order to apply a high magnetic field to the driving coil 104.
In mirror structures such as the optical deflector mirror portion 100, the surface of the support on a driving coil side is utilized as a bonding surface with the fixing member. Since a power supply pad for the driving coil is usually formed on the surface of the support on the driving coil side, it is difficult to secure a flat surface with an area sufficient for bonding.
Moreover, in the mirror structure the support is bonded to the fixing member with the power supply pad directed to the fixing member. Therefore, in order to draw wiring out of the power supply pad, an anisotropic conductive film (ACF), and the like need to be used to connect wiring materials such as a flexible wiring board (FPC) to the mirror structure before bonding the structure to the fixing member. This restriction deteriorates operation efficiency during bonding to the fixing member, and also deteriorates positioning precision.
Furthermore, since the surface of the mirror structure on the driving coil side is attached to the fixing member, the magnetic yoke or the fixing member needs to be processed in a complicated shape in order to dispose the magnetic yoke in the vicinity of the driving coil.